We aimed to assess the quality of charcoal from three Eucalyptus and Corymbia citriodora species for energy production in the South of Tocantins state. A hybrid Eucalyptus urophylla x Eucalyptus grandis, the species Eucalyptus urophylla, Eucalyptus camaldulensis, and Corymbia citriodora were selected for the study. In the preparation of the material, 20 specimens of each species with the dimensions of 2.0 x 2.0 x 5.0 cm were made, being ten repetitions for each carbonization gait with different final temperatures and heating rates. The basic wood density, total gravimetric yield, total yields in condensable and non-condensable gases, immediate chemical analysis, and higher calorific value were determined. Corymbia citriodora presented higher wood basic density (0.583 g/cm³) and charcoal apparent density (0.459 g/cm³). In immediate chemical analysis, Eucalyptus urophylla and Corymbia citriodora presented the best averages among all species. The calorific value ranged from 7235.97 to 7573.98 (kcal/kg), considered an acceptable value for energy production. The final carbonization temperature of 550°C is recommended, with Eucalyptus urophylla and Corymbia citriodora presenting the best averages.

Objetivo: O objetivo deste trabalho foi avaliar o comportamento da madeira da espécie Eucalyptus urophylla × Eucalyptus grandis estocada ao ar livre durante o período de sete meses, para a determinação de seus ganhos e perdas energéticas. Foram utilizadas árvores com cerca de 13 anos, transformadas em toretes de um metro, uma parte para ser estocada ao ar livre por sete meses, outra para análise da madeira recém-coletada. Para ambas as análises os toretes foram transformados em discos depois em cavacos, uma parte utilizada na determinação das densidades da madeira e produção do carvão vegetal, outra parte transformada em partículas para as análises químicas. As propriedades físicas da madeira apresentaram perdas durante o tempo de estocagem, enquanto o teor de lignina (20,99 a 24,02 %) e solubilidade em (NaOH) (13,53 a 21,42 %) aumentaram. Nas propriedades energéticas tanto da madeira como do carvão vegetal, as madeiras estocadas por sete meses apresentaram baixa densidade energética (2095,49 e 968,36 kcal/m -3 , respectivamente) altos teores de materiais voláteis (84,71 e 61,45 %, respectivamente) e altos valores de carbono fixo (15,1 e 80,92 %, respectivamente) e poder calorífico. O tempo de estocagem afetou de forma negativa nas propriedades físicas da madeira, principalmente sua densidade, onde acabou impactando na densidade energética tanto da madeira quando do carvão vegetal, reduzindo assim a quantidade de energia por unidade de massa, entretanto apresentaram bons resultados de carbono fixo e poder caloríficos, demostrando o seu potencial na geração de energia.

The objective of the research was to characterize the energetic properties of the charcoal from species from the cerrado sensu stricto, as well as to evaluate the effect of the final carbonization temperature. Five species were selected for study. Ten specimens were obtained from the logs of each species, submitted to two treatments with five replicates each. The basic density of the wood was calculated by the hydrostatic balance method. The charcoal was produced by the pyrolysis process of the wood in a muffle furnace adapted to capture the pyrolignous liquor, in which two heating speeds were used with final temperatures of 500 °C and 550 °C. Through the pyrolysis process, the total gravimetric yield of the coal, yield in condensable gas, and non-condensable gas were obtained. The apparent density, the immediate chemical analysis (ICA) of the charcoal was determined and, finally, its calorific value was calculated. The YC presented acceptable values for the species Terminalia glabrescens (35.43%) and Vatairea macrocarpa (32.59%). The volatile material content of Vatairea macrocarpa (22.53%) presented satisfactory values. Fixed carbon, ash and heat content were also considered acceptable for the species Terminalia glabrescens (74.43%, 0.96% 7457.40 kcal.kg-¹), Vatairea macrocarpa (75.21% 0.55% and 7443.57 kcal.kg-¹) and Xylopia aromatica (74.27%, 0.67% and 7365.56 kcal.kg-¹), presenting high energy potential. The YC, YL and YNNC were influenced by the heating speeds as well as the content of volatile materials. The recommended final carbonization temperature is 550 °C.

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